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Wiki Sudden Loss Of Range With 2019.16.x Software
- Thread starter Dutchmeeuw
- Start date
Porsche investigates alleged manipulation of petrol engines | Autocar
"investigations into alleged software and hardware changes made to engines after they were type-approved by Germany’s Federal Motor Transport Authority"
We get to see how Germany will handle Tesla, though Porsche is going public first which may help get more leniency. I doubt batterygate was ever "type approved" anywhere.
"investigations into alleged software and hardware changes made to engines after they were type-approved by Germany’s Federal Motor Transport Authority"
We get to see how Germany will handle Tesla, though Porsche is going public first which may help get more leniency. I doubt batterygate was ever "type approved" anywhere.
faughtz
Model S P85DL
Well, so far we have cell internal high ir effects and plating / shorting effects and external we have balancing circuit 'shorts' or open circuits as contenders.......
Not sure if either thermal management or mechanical integrity related has been considered a possibility......
That's a cool project. And handy that it uses 85 packs. Is it still active?
This:
was the exact reason I started following this thread last August.
I still find it somewhat unbelievable that 100mA or so can keep the bricks balanced, although since balancing just bleeds off energy, you hardly want to be bleeding off loads.
The bigger the disparity between brick conditions, the harder the bleed circuits have to work, and likely working at higher temperatures due to increased internal cell heat dissipation. At higher temperatures the dissipation capability of the bleed circuit will reduce too. IF the bleed resistors were already in an ambient of say 45 to 50 Celcius, their dissipation would certainly be effected. Limiting charge current and increasing charging time would help compensate for a compromised balancing system, but can't immediately see how that would link to needing to limit max cell voltage which still seems more plating / shorting related. I guess capping Vmax maybe gives a bit more overall headroom.
And still very odd to have no bulletin / recall requiring changes to all potentially effected cars.
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I suppose the lower voltage cap is the belt and braces. The slower charging would be to give an imbalanced pack / maybe compromised balancing system chance to still get a reasonable amount of energy into the battery before a brick reaches Vcap.
If that is the case, then the worst case for old software is that one brick reaches the original Vmax (4.2v?) faster and faster, resulting in more unreachable capacity in all the other cells. As long as you voluntarily limit charge to say 80% (that is a problematic statement though) then you should stay well away from 4.2v in any case. And if your cells are in good shape then your charge will be spread fairly evenly.
I don't know how SOC limits are determined. By net charge into the battery or by transient voltage readings or some other means. I suspect it would ideally ignore voltage as long as it remains within set limits.
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They had a legally defined 60 day deadline to inform owners from the instant they discovered the issue and the clock started before they released a public statement and took action. Taking action that violates Warranty law multiplies the eventual punishments (See Porsche's recent announcement they are investigating themselves and voluntarily reporting their own crimes to avoid another CEO sent to jail over illegal software changes - they take things like this seriously!), and they were already in trouble for not reporting and probably had no actual fix (and maybe never will). When they missed the (USA) legal deadlines with indications they still had a safety problem post-notification someone very high up at Tesla must have made the decision to go into Denial Mode. Takata employees were criminally charged for concealing safety issues already and VW's CEO imprisoned for reducing range using post-certification software changes so Tesla's executive decision maker probably felt they were backed into a corner by their crimes and decided not to come clean. Or, maybe there is a new hardware that needed to be invented (like the 350V battery that has more capacity than the 90s, but is labeled "85" and only used as a replacement for older cars) and they thought they could beg for forgiveness when they engineered a way out of this mess.
Thanks for the circuit board information. I'm still researching it and like you having a tough time reconciling all of the 'Gates to that part but it is a promising hypothesis.
On an unrelated tangent, the 350 volt replacement 85 might be 350 volts for a good reason. Reading up on Tesla's Chinese language public statements regarding several batterygate-apparent fires (I wasn't aware of them all myself, there were more than we linked here last year), they seem to indicate module 8 or 9 was the source of the fire. Those are the 2 modules stacked on top of one another at the front of the pack with the worst cooling, and those 2 modules aren't installed in the redesigned 350 volt packs.
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I can't say I have seen hard evidence of any failure. It's all informed guessing (at least on my part).
Here is a little more behind my thinking.
In case you hadn't picked up already from wk057's much earlier post, those 6 banks of 4 X 158 ohm resistors (labelled 1580 in the cropped image above) are the heat dissipating components that are connected across each of the 6 bricks in a module to (try and) keep the charge / energy balanced between them. Balancing is done based on evidence of brick performance during previous use and is (now) applied during both charging and discharging. I don't know if people are generally aware of heat energy dissipation vs ambient temperature, but while those little resistors probably dissipate a maximum of 0.25 or 0.5 watt in free air at 20 degrees Celcius, that reduces markedly as ambient temps rise. There was mention of the actual rated dissipation earlier in the thread. To be quite honest, it feels completely impossible to me that those tiny resistors (albeit quite a few of them) are all that's needed to keep a pack energy-balanced. But I get that the longer they have current passing through them, the more energy they can dissipate, as well as by keeping their ambient temperature as low as possible. It was discussed much earlier that there is no cooling provision specifically for those balancing resistors but iirc that idea was just left hanging.
The electronic switch that connects the resistors in and out of circuit (a mosfet according to wk057 and others) will also be rated for max current and (small) dissipation due to its own (low) resistance when conducting. Again, high ambient temps usually compromise the ratings.
With regards to what might fail or be problematic, someone with more direct experience could probably answer that better. It would depend on if the resistors were getting left permanently connected - creating unwanted drain and imbalance, or becoming permanently open circuit and incapable of contributing to balancing.
With it appearing that multiple factors are all at play, and without much hard evidence, it is not easy to determine what relates to what. For example, if David99's 'short' message refers to something internal to the cell chemistry or external as in the balancing circuits. Multiple effects working in the same direction are also problematic, so cell aging linked with plating, higher internal resistance and internal shorting can all be present (maybe not all simultaneously) and be responsible for higher temperatures in the battery. Meanwhile, the balancing system that has more work to do because of the imbalances, now also has to work at higher ambient temperatures.
@BigNick shared some battery data with me in addition to what he posted here and within the limits of what he shared it didn't contradict my ideas.
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Wk057 is throwing down some pretty strong hints that it's these electronic components that are the issue.
But if that were the case, why is Tesla not just replacing these boards? Can't these boards be replaced without disassembling the battery modules?
Is it just that there is too much labor involved in bringing in thousands of cars to disassemble their packs and replace these boards?
But if that were the case, why is Tesla not just replacing these boards? Can't these boards be replaced without disassembling the battery modules?
Is it just that there is too much labor involved in bringing in thousands of cars to disassemble their packs and replace these boards?
Just wild speculation, but if the resistors are being left permanently connected, capping the voltage would reduce the amount of energy they are dissipating / heat they are generating. Maybe this is what the "weak short" message is. Or the MOSFET themselves are damaged and dissipating more energy than they are supposed to.
But, that theory doesn't seem to make too much sense because the voltage caps being applied are only like 3%.
Running the cooling until SOC gets down to 80% also would alleviate issues related to leaving them connected. That significantly reduces the voltage of the pack.
How close are these boards to the coolant lines? Reducing the temperature of the whole pack would also allow heat generated by these resistors to be absorbed more easily.
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Just using david's hard evidence we know Tesla's "BMS_W117" error is intentionally hiding shorts the system has identified from us owners, so Tesla is both identifying a safety issue and actively concealing it - "(hidden) [no audience]" is how Tesla labels that specific short detection.
Tesla then goes on in the same hard evidence to show the error BMW_u025 is another "[Hidden] (service, factory)" problem they want to conceal from the owner. This one clearly states a warranty violation is occurring - in plain English describing David's batterygate problems in Tesla's exact words as "Charge settings adjusted. Indicates limit on brick voltage is in effect."
This hard evidence directly told us Tesla was using voltage limits to batterygate us, and simultaneously links the problem to short circuits that are detected, but hidden so they would not alert the owner the car needs immediate warranty service for safety and usability's sake. Neither situation is legal. Detecting electrical shorts and hiding them so they aren't repaired is a safety violation. Intentionally reducing performance to save money on warranty repairs is a warranty violation.
The hard evidence we have says Tesla is breaking laws. We're circling around why a lot, but in the end that answer is for the courts. All we want - all of us, affected owners and unaffected nonowners alike - is for Tesla to adhere to the law and be the safe, reliable, good company we bought when they enticed us with claims of being the safest cars ever made with the world's best warranty.
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I suspect that without a means of dissipating the balancing energy, you might not actually address the problem.
I wonder what makes say the 100 packs any better? Is it better thermal management keeps pack temps lower, thus aiding the balancing dissipation? Or better matched cells that don't need as much balancing? Or just putting more stringent control on operating loads so the cells gets less stress?
Maybe they have made revisions to the boards in the newer packs? Or maybe they're just not old enough to start failing yet.
Do we know that there is no improved cooling on the module boards in the new packs?
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